1. Field of the Invention
The present invention relates to a method of manufacturing an illumination optical unit, an apparatus for manufacturing an illumination optical unit, an illumination optical unit manufactured by the manufacturing method, and a projector.
2. Description of Related Art
Projectors including a light source lamp, an electro-optical device for modulating beams emitted from the light source lamp according to image information and a projection optical system for enlarging and projecting the beams modulated by the electro-optical device have been used in the related art.
In such projector, in order to evenly and uniformly illuminate an image forming area of the electro-optical device with the beams emitted from the light source lamp, an illumination optical system composed of a plurality of optical elements is interposed between the light source lamp and the electro-optical device.
The illumination optical system is constituted by, for example, a beam splitting element for splitting the light emitted from a light source lamp into a plurality of partial beams, a light focusing element for focusing the plurality of split partial beams on the image forming area of the electro-optical device, and a polarization converting element for making polarization directions of the beam emitted from the light source lamp uniform in a substantially identical direction.
In the case of adjusting such an illumination optical system, in the related art, the light source lamp, the beam splitting element, the light focusing element, the polarization converting element and the electro-optical device are installed in an optical component casing for receiving these optical components. Also, the positions of the beam splitting element, the light focusing element and the polarization converting element are adjusted while actually projecting the beams emitted from the light source lamp on a screen by determining the brightest position having no unevenness as the optimal position as seen with the naked eye.
Recently, miniaturization of the projector entailed need for shortening the length of an optical path from the light source lamp to the electro-optical device and for improving light focusing efficiency by the illumination optical system interposed between the light source lamp and the electro-optical device.
However, in case of adjusting the related art illumination optical system, the positions of the beam splitting element, the light focusing element and the polarization converting element are respectively adjusted with respect to the optical component casing, and thus it is difficult to perform the position adjustment of these optical components with high precision.
Moreover, because the optimal positions of those optical components are determined with the naked eye from the optical image projected on a screen, it is possible that the accuracy of adjustment varies depending on a person who adjusts the positions, or the accuracy of adjustment deteriorates with the lapse of a working time.
A method is desirable to make the optical elements unit in order to improve the focusing efficiency by the illumination optical system by adjusting the positions of the plurality of optical elements with a high precision degree.